2010-07-07 11:12:45 +00:00
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From: Suresh Jayaraman <sjayaraman@suse.de>
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Subject: [PATCH] mm: Make default VM dirty ratio configurable to suit different workloads
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References: bnc#552883
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Patch-mainline: Never
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Based on the observation that higher VM dirty ratio improves performance of
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most server workloads that dirties a lot of memory (e.g. simple databases not
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using direct IO, workloads doing heavy writes) and the latency-sensitive
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workloads like desktop and typical workstations perform better with a
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decreased VM dirty ratio, make default VM dirty ratio configurable. This also
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ensures that we have the similar dirty pages writeback limit in SLES11 SP1 as
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compared to SLES11 GM.
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The default VM dirty ratio is 20 for kernel-desktop flavor and 40 for all the
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other flavors.
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Also introduce a new CONFIG_KERNEL_DESKTOP option which might allow to tune
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the kernel to suit desktop workloads.
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Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
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Acked-by: Jiri Kosina <jkosina@suse.cz>
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Acked-by: Jeff Mahoney <jeffm@suse.com>
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---
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init/Kconfig | 24 ++++++++++++++++++++++++
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mm/page-writeback.c | 2 +-
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2 files changed, 25 insertions(+), 1 deletion(-)
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--- a/init/Kconfig
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+++ b/init/Kconfig
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2011-04-19 20:09:59 +00:00
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@@ -32,6 +32,12 @@ config SPLIT_PACKAGE
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2010-07-07 11:12:45 +00:00
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If you aren't packaging a kernel for distribution, it's safe to
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say n.
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+config KERNEL_DESKTOP
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+ bool "Kernel to suit desktop workloads"
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+ help
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+ This is an option used to tune kernel parameters to better suit
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+ desktop workloads.
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+
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config ARCH
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string
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option env="ARCH"
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2011-04-19 20:09:59 +00:00
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@@ -1169,6 +1176,23 @@ config MMAP_ALLOW_UNINITIALIZED
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2010-07-07 11:12:45 +00:00
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See Documentation/nommu-mmap.txt for more information.
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+config DEFAULT_VM_DIRTY_RATIO
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+ int "Default VM dirty ratio (in %)"
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+ default 20 if KERNEL_DESKTOP
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+ default 40
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+ help
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+ Allows to tune VM dirty ratio to suit different workloads. Increased
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+ VM dirty ratio improves performance of most server workloads that
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+ dirties a lot of memory (e.g. simple databases not using direct IO,
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+ workloads doing heavy writes). The latency-sensitive workloads like
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+ desktop and typical workstations perform better with a decreased
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+ VM dirty ratio.
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+
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+ Recommended value for desktop workload is 20.
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+ Recommended value for server workload is 40.
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+
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+ Only use this if you really know what you are doing.
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+
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config PROFILING
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bool "Profiling support"
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help
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--- a/mm/page-writeback.c
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+++ b/mm/page-writeback.c
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2011-04-19 20:09:59 +00:00
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@@ -78,7 +78,7 @@ int vm_highmem_is_dirtyable;
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2010-07-07 11:12:45 +00:00
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/*
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* The generator of dirty data starts writeback at this percentage
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*/
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-int vm_dirty_ratio = 20;
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+int vm_dirty_ratio = CONFIG_DEFAULT_VM_DIRTY_RATIO;
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/*
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* vm_dirty_bytes starts at 0 (disabled) so that it is a function of
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